The Fragility Index of randomized controlled trials in pediatric anesthesiology.

PURPOSE: The P value is a widely used measure of statistical importance but has many drawbacks and limitations, one being that it does not reflect the robustness of the results of a clinical trial. The Fragility Index (FI) was developed as a measure of how many outcome events would need to change to nonevents to render a significant P value nonsignificant (P ≥ 0.05). The FI of trials from other medical specialties is typically < 5. We aimed to determine the FI of pediatric anesthesiology randomized controlled trials (RCT) and to test for association with various characteristics of the included trials.

METHODS: We conducted a comprehensive systematic search of high-impact anesthesia, surgical, and medical journals from the last 25 years for trials comparing an intervention between two groups with a statistically significant P value (< 0.05) for a dichotomous outcome. We also compared FI values for variables that reflect the quality and importance of a trial.

RESULTS: The median [interquartile range] FI was 3 [1-7] and correlated positively with the number of participants (rS = 0.41; P < 0.001) and events (rS = 0.42; P < 0.001), and negatively with the P value (rPB = -0.36; P < 0.001). Other measures of trial quality and impact or importance were not strongly associated with the FI.

CONCLUSIONS: The FI of published trials in pediatric anesthesiology is similarly low as in other medical specialties. Larger trials with more events and P values ≤ 0.01 were associated with a higher FI.